The proposed project, to be conducted at the Michaelson Institute for the Prevention of Blindness, in association with the Public Health Services of the Jerusalem Municipality, is a case-control (retrospective) study designed to examine the association between childhood amblyopia and strabismus and selected perinatal factors. The study will be nested within a screening program to be conducted on the approximately 27,000 children born in Jerusalem between March 1984 and April 1987, who are registered in the local Mother and Child Health (MCH) Centers. The majority of these children will be aged 3.0-4.9 years during the examination period. The study is scheduled to run from Sept. 1988-Aug. 1991. Demographic information regarding the child and parents will be obtained via a questionnaire to be completed by the parents, with extensive telephone and personal follow-up to assure maximum response. The screening, to be performed by students of the Hebrew University-Hadassah School of Nursing who will be trained and supervised by the Institute staff, will be carried out along two simultaneous tracks: children attending an educational framework will be examined within the nursery setting, and those not attending nurseries will be examined at home. The screening test will consist of a Random Dot E Stereotest and a visual acuity test, which will follow a detailed standardized protocol Those children found positive on the screening will be referred to the Institute for a set of definitive diagnostic examinations, to be performed in the presence of a parent who will supply background information. A control group will be invited for an identical set of examinations from among those children who were negative on screening, to enable the calculation of more exact prevalence estimates of the disorders for the total population and for specific subgroups, as well as to evaluate the screening tests in terms of sensitivity, specificity and predictive values. Application of the screening test at ages 3-4 will be compared to the current practice in Jerusalem, of screening at the younger ages of 6-24 months. The case-control study will assess the effect of maternal and infant related pre-, peri- and post-natal factors on the development of amblyopia and/or strabismus. Information regarding such factors will be obtained from the parental questionnaire and the pregnancy/delivery records from the MCH Centers and the relevant hospitals.